transmittal of report addressing additional information needs … · the conclusion of this report...

Department of Energyj ?- lgl Office of Civilian Radioactive Waste Management QA: N/A

Office of Repository Development Project No. WM-0001P.O. Box 364629North Las Vegas, NV 89036-8629

AUG 2 9 2003

OVERNIGHT MAIL

ATTN: Document Control DeskChief, High-Level Waste Branch, DWMINMSSU.S. Nuclear Regulatory Commission11555 Rockville PikeRockville, MD 20852-2738

TRANSMITTAL OF REPORT ADDRESSING ADDITIONAL INFORMATION NEEDS(AIN) FOR KEY TECHNICAL ISSUE (KTI) AGREEMENTS TOTAL SYSTEMPERFORMANCE ASSESSMENT AND INTEGRATION (TSPAI) 2.05 AND 2.06

References: (1) Ltr, Schlueter to Ziegler, dtd 8/2/02(2) Ltr, Brocoum to Schlueter, dtd 4/5/02

This letter transmits KTI Letter Report, Response to Additional Information Needs onTSPAI 2.05 and TSPAI 2.06, REG-WIS-PA-000003, Revision 00, ICN 04, which providesadditional information in response to Reference 1.

The subject KTI agreements were originally addressed in the U.S. Department of Energy (DOE)document The Enhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain,submitted in Reference 2. After reviewing this document, the U.S. Nuclear RegulatoryCommission (NRC) identified nine AINs for Agreement TSPAI 2.05 and five AINs forAgreement TSPAI 2.06 that must be addressed to complete these KTI agreements. The enclosedreport addresses each of these AINs and provides clarification of items described in TheEnhanced Plan for Features, Events, and Processes (FEPs) at Yucca Mountain.

The conclusion of this report refers to the DOE's proposal to meet periodically with the NRC toprovide progress assessments. This process began with a demonstration of the Enhanced FEPsDatabase to on-site NRC representatives in Las Vegas, Nevada, on June 6, 2003. As noted inReference 1, TSPAI KTI agreement item 2.06 may be satisfied without the need for additionalmeetings.

The DOE considers Agreements TSPAI 2.05 and 2.06 to be fully addressed by the enclosedreport, and, pending review and acceptance by the NRC, they should be closed.

Chief, High-Level Waste Branch -2- AUG 2 9 2003

There are no new regulatory commitments in the body or enclosure to this letter. Please directany questions concerning this letter and its enclosure to Carol L. Hanlon at (702) 794-1324 orMark C. Tynan at (702) 794-5457.

fo/eph~b. ZiegI4,Dk'ectorOLA&S:TCG-1 131 Ofice of Licel Application and Strategy

Enclosure:KTI Letter Report, Response to Additional

Information Needs on TSPAI2.05 andTSPAI 2.06, REG-WIS-PA-000003,Revision 00, ICN 04

cc w/encl:G. P. Hatchett, NRC, Rockville, MDD. D. Chamberlain, NRC, Arlington, TXR. M. Latta, NRC, Las Vegas, NVD. B. Spitzberg, NRC, Arlington, TXH. J. Larson, ACNW, Rockville, MDW. C. Patrick, CNWRA, San Antonio, TXBudhi Sagar, CNWRA, San Antonio, TXJ. R. Egan, Egan & Associates, McLean, VAJ. H. Kessler, EPRI, Palo Alto, CAM. J. Apted, Monitor Scientific, LLC, Denver, COSteve Kraft, NEI, Washington, DCW. D. Barnard, NWTRB, Arlington, VAR. R. Loux, State of Nevada, Carson City, NVMajorie Paslov Thomas, State of Nevada, Carson City, NVAlan Kalt, Churchill County, Fallon, NVIrene Navis, Clark County, Las Vegas, NVGeorge McCorkell, Esmeralda County, Goldfield, NVLeonard Fiorenzi, Eureka County, Eureka, NVAndrew Remus, Inyo County, Independence, CAMichael King, Inyo County, Edmonds, WAMickey Yarbro, Lander County, Battle Mountain, NVSpencer Hafen, Lincoln County, Pioche, NVLinda Mathias, Mineral County, Hawthorne, NVL. W. Bradshaw, Nye County, Pahrump, NVJosie Larson, White Pine County, Ely, NVR. I. Holden, National Congress of American Indians, Washington, DCAllen Ambler, Nevada Indian Environmental Coalition, Fallon, NV

Chief, High-Level Waste Branch -3- AUG 2 9 2003

cc w/o end:C. W. Reamer, NRC, Rockville, MDA. C. Campbell, NRC, Rockville, MDL. L. Campbell, NRC, Rockville, MDJ. D. Parrott, NRC, Las Vegas, NVN. K. Stablein, NRC, Rockville, MD

QA: NA

REG-WIS-PA-000003 REV 00 ICN 04

August 2003

KTI Letter Report

Response to Additional InformationTSPAI 2.05 and TSPAI 2.06

Needs on

ByG. Freeze

Prepared forU.S. Department of EnergyOffice of Civilian Radioactive Waste ManagementOffice of Repository DevelopmentP.O. Box 364629North Las Vegas, Nevada 89036-8629

Prepared by:Bechtel SAIC Company, LLC1180 Town Center DriveLas Vegas, Nevada 89144

Under Contract NumberDE-AC28-01 RW12101

ENCLOSURE

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neitherthe United States Government nor any agency thereof, nor any of their employees, nor any of their contractors,subcontractors or their employees, makes any warranty, express or implied, or assumes any legal liability orresponsibility for the accuracy, completeness, or any third party's use or the results of such use of any information,apparatus, product, or process disclosed, or represents that its use would not inffinge privately owned rights.Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, orotherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the UnitedStates Government or any agency thereof or its contractors or subcontractors. The views and opinions of authorsexpressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

REG-WIS-PA-000003 REV 00 ICN 04 August 2003

KTI Letter Report-Response to Additional Information Needs on TSPAI 2.05 and TSPAI 2.06REG-WIS-PA-000003 REV 00 ICN 04August 2003

Prepared by:

J;f. 1.1 ,Features, Events, and Processes

2 ?- 0Date

Dat /

Checked by:

/?!Graes, Performance Assessment Strategy and Scope Project

Approved by:

link, Decision Support and Documentation Department Manager Date


CHANGE HISTORY

RevisionNumber

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Interim Date ofChange No. Revision

0 03/21/03

1 03/31/03

2 04/25/03

3 07/24/03

4 08/25/03

Description of Change

Initial Issue.

Editorial Changes in response to AP-REG-014,Information for Material or Regulatory Responsereview of transmittal letters. No change bars shown.

Editorial Changes in response to additional LAPcomments. No change bars shown.

Editorial Changes in response to DOE comments. Nochange bars shown.

Editorial Changes in response to DOE comments. Nochange bars shown.

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REG-WIS-PA-000003 REV 00 ICN 04 Al August 2003

TABLE OF CONTENTS

Page

ACRONYMS AND ABBREVIATIONS ..................................................... xi

1. BACKGROUND ...... ................. .. 1.............................1.1 NRC COMMENTS ON THE KTI LETTER REPORT .................................................. 21.2 PROPOSED RESOLUTION ...................................................... 2

2. DETAILS OF THE PROPOSED RESOLUTION ..................................................... 32.1 ADDITIONAL INFORMATION NEEDS FOR TSPAI 2.05 ............................ ............. 62.2 ADDITIONAL INFORMATION NEEDS FOR TSPAI 2.06 ......................................... 9

3. CONCLUSIONS..................................................................................................................... 11

4. REFERENCES ...................................................... 114.1 DOCUMENTS CITED ..................................................... 1 14.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES ............................. 12

REG-WIS-PA-000003 REV 00 ICN 04 .i. August 2003


REG-WIS-PA-000003 REV 00 ICN 04 viii August 2003

FIGURES

Page

1. Sample figure showing subsystem and process hierarchy approach .................................. 4

2. Example of a listing produced when the Waste Package - Mechanical cell isselected in Figure 1 .5

REG-WIS-PA-000003 REV 00 ICN 04 ix August 2003


REG-WIS-PA-000003 REV 00 ICN 04 x August 2003

ACRONYMS AND ABBREVIATIONS

AIN Additional Information NeedAMR Analysis/Model Report

DOE U.S. Department of Energy

FEPs features, events and processes

KTI Key Technical Issue

LA License Application

NEA Nuclear Energy AgencyNRC U.S. Nuclear Regulatory Commission

SR Site Recommendation

TSPA total system performance assessmentTSPAI Total System Performance Assessment and Integration

REG-WIS-PA-000003 REV 00 ICN 04 xi August 2003


REG-WIS-PA-000003 REV 00 ICN 04 xii August 2003

1. BACKGROUND

This report addresses additional information needs (AINs) on Total System PerformanceAssessment and Integration (TSPAI) Key Technical Issue (KTI) Agreement items 2.05 and 2.06.These agreements between the U.S. Department of Energy (DOE) and the U.S. NuclearRegulatory Commission (NRC) read (NRC 2002, p. A-28) as follows:

TSPAI 2.05: "It is not clear to the NRC that the current list of FEPs (i.e., the list of FEPsdocumented in TDR-WIS-MD-000003, 00/01) is sufficiently comprehensive or exhibits thenecessary attribute of being auditable (e.g., transparent and traceable). As discussed in the twoTSPAI technical exchanges, there are unclear aspects of the approach that DOE plans to use todevelop the necessary documentation of those features, events, and processes that they haveconsidered. Accordingly, to provide additional confidence that the DOE will provide NRC with:(1) auditable documentation of what has been considered by the DOE, (2) the technical basis forexcluding FEPs, and (3) an indication of the way in which included FEPs have been incorporatedin the performance assessment; DOE will provide NRC with a detailed plan (the Enhanced FEPPlan) for comment. In the Enhanced FEP Plan, DOE will address the following items: (1) theapproach used to develop a pre-screening set of FEPs (i.e., the documentation of those things thatDOE considered and which the DOE would use to provide support for a. potential licenseapplication), (2) the guidance on the level-of-detail that DOE will use for redefining FEPs duringthe enhanced FEP process, (3) the form that the pre-screening list of FEPs will take (e.g., list,database, other descriptions), (4) the approach DOE would use for the ongoing evaluation ofFEPs (e.g., how to address potentially new FEPs), (5) the approach that DOE would use toevaluate and update the existing scope and description of FEPs, (6) the approach that DOEwould use to improve the consistency in the level of detail among FEPs, (7) how the DOE wouldevaluate the results of its efforts to update the existing scope and definition of FEPs, (8) how theenhanced FEP process would support assertions that the resulting set of FEPs will be sufficientlycomprehensive (e.g., represents a wide range of both beneficial and potential adverse effects onperformance) to reflect clearly what DOE has considered, (9) how DOE would indicate theirdisposition of included FEPs in the performance assessment, (10) the role and definition of thedifferent hierarchical levels used to document the information (e.g., "components of FEPs" and"modeling issues"), (11) how the hierarchical levels used to document the information would beused within DOE's enhanced FEP process, (12) how the Enhanced FEP Plan would result indocumentation that facilitates auditing (i.e., lead to a process that is transparent and traceable),(13) DOE's plans for using configuration management controls to identify FEP dependencies onongoing work and design changes. DOE will provide the Enhanced Plan to NRC byMarch 2002."

TSPAI 2.06: "Provide justification for the approach to: (1) the level of detail used to defineFEPs; (2) the degree of consistency among FEPs; and (3) comprehensiveness of the set of FEPsinitially considered (i.e., before screening). DOE proposes to meet with NRC periodically toprovide assessments of the DOE's progress, once it has initiated the enhanced FEP process, andon changes to the approach documented in the Enhanced FEP Plan. During these progressmeetings DOE agrees to provide a justification for their approach to: (1) the level of detail usedto define FEPs; (2) the degree of consistency among FEPs; and (3) comprehensiveness of thepre-screening set of FEPs."

REG-WIS-PA-000003 REV 00 ICN 04 I August 2003

By letter dated April 5, 2002, DOE provided information pertaining to TSPAI Agreement 2.05(Brocoum 2002) by transmitting the Enhanced Plan for Features, Events and Processes (FEPs)at Yucca Mountain (BSC 2002) (referred to as the Enhanced FEP Plan hereafter) to the NRC.Subsequently, during a Technical Exchange and Management Meeting held on April 15-16,2002, DOE requested that NRC review the information provided on April 5, 2002, as it pertainsto TSPAI Agreement 2.06 (Schlueter 2002a).

As stated in its April 5, 2002 letter (Brocoum 2002), the additional information contained in theEnhanced FEP Plan (BSC 2002) describes the DOE approach for developing the documentationof considered FEPs. Section 3.3 of the Enhanced FEP Plan summarizes the plan basis foraddressing each of the items in TSPAI 2.05. With regard to TSPAI 2.06, the Enhanced FEP Planincludes justification for the approach used to determine the level of detail used to define FEPs,the degree of consistency among FEPs, and the comprehensiveness of the set of FEPs initiallyconsidered (i.e., before screening). DOE expected that the information presented in theEnhanced FEP Plan would address the documentation aspects of the agreements. DOE alsoagreed to meet with the NRC periodically to provide assessment of progress on implementing theEnhanced FEP Plan.

1.1 NRC COMMENTS ON THE KTI LETTER REPORT

The NRC staff determined that the Enhanced FEP Plan (BSC 2002) does not fully satisfy theintent of the TSPAI Agreement 2.05. "The Enhanced FEP Plan does address, at some level, eachof the thirteen items listed in the agreement. However, the Enhanced FEP Plan does not clarify anumber of unclear aspects of DOE's approach, nor does it provide, in some areas, theinformation and detail that would give the NRC staff confidence that DOE's approach wouldresult in the information necessary to allow a detailed review of this part of a potential licenseapplication." (Schlueter 2002b)

The NRC staff also determined that the Enhanced FEP Plan does not provide the information ordetail necessary to allow a detailed review of DOE's initial (or pre-screening) list of FEPs."Based on the information contained in the Enhanced FEP Plan, additional information is neededbefore the intent of TSPAI Agreement 2.06 is satisfied. This information is needed to enable thestaff to conduct a detailed review of the potential license application and does not need to beconveyed in conjunction with future NRC/DOE interactions." (Schlueter 2002b)

Specific additional information needs were identified in 14 AINs (nine for TSPAI 2.05 and fivefor TSPAI 2.06) (Schlueter 2002b). These AINs requested clarification of schedule, methods ofaggregating FEPs and the resulting level of detail, FEPs with mixed include and excludedecisions, demonstration of completeness, and auditability.

1.2 PROPOSED RESOLUTION

Changes are being made in the FEP documentation system, as documented in the Enhanced FEPPlan (BSC 2002). These changes are to address KTI TSPAI Agreements 2.05 and 2.06, and theadditional information needs in the NRC letter (Schlueter 2002b). Additional changes to theFEP documentation system are described herein; the changes are supplemental to and, in somecases, supercede the enhancements initially documented in the Enhanced FEPs Plan (BSC 2002).

REG-WIS-PA-000003 REV 00 ICN 04 2 August 2003

The additional changes are necessary to better address the KTI TSPAI Agreements 2.05 and2.06, and to further improve clarity. The additional changes, discussed in Section 2 below,address the additional information needs with respect to further clarification and consideration ofsuggested improvements. The information provided herein clarifies and modifies the approachdescribed in the Enhanced FEP Plan, which will not be revised.

2. DETAILS OF THE PROPOSED RESOLUTION

The Enhanced FEP Plan (BSC 2002, Section 3.2.1) identified the development of a FEP matrixconstructed from multiple hierarchical levels to classify FEPs and promote navigation within thedatabase, that documents the FEP list and screening decision in a single consolidated location. Italso identified criteria for FEPs and FEP components to define the level of detail. To address thereview comments and AINs identified in Schlueter (2002b), the following general changes arebeing implemented.

As described in the Enhanced FEP Plan, FEPs will be aggregated to the coarsest level at which atechnically sound screening decision can be made. However, in a change subsequent to theEnhanced FEP Plan, FEP components will not be used to identify finer details of a FEP. Insteada list of keywords for each FEP will be added to facilitate navigation and enhance the ability ofdatabase users to find the treatment of specific finer details within a FEP. Additionally, theentire list of Nuclear Energy Agency (NEA) FEPs (which provided the basis for some of thefiner details formerly represented by secondary FEPs) will be mapped in the database to theYucca Mountain FEPs to help confirm that finer details have been addressed.

The matrix of physical subsystems versus processes described in Section 3.2.1 of the EnhancedFEP Plan (BSC 2002) will be improved. The physical system will be developed in threehierarchical levels. Similarly, the process hierarchy will include three levels. Figure 1 hereinshows this conceptually. The intersection of any third level process (or event) with any thirdlevel physical subsystem (or feature) will define the level at which FEPs and keywords will beassociated with the subsystem and process description of the repository. For each of theseintersections that is a credible combination of process and subsystem, there will be associatedFEPs and keywords. Figure 2 herein shows one potential example. The database will identifyall FEPs and keywords associated with a process-subsystem combination. There will be nosecondary FEPs or FEP components.

The database will allow navigation using the physical subsystem or process hierarchies (i.e.,from the matrix), and in reverse from the FEP list or keyword list. The FEPs and keywords willbe linked to the NEA classification list (for completeness) and the SR FEP list (for traceability),with forward or reverse navigation.


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Legend:

The specific subsystems and processes, and the example entries in the table are for illustration only.

Shading indicates the combination of subsystem and process is not applicable to the repository.Numbers in a cell indicate the number of Included FEPs and the number of Excluded FEPs [e.g. Waste Package - Mechanical has 1 Included FEP and 4 Excluded FEPsI.

Figure 1. Sample figure showing subsystem and process hierarchy approach

.FEP Name: Eary failure of aste packagesFEP Number: 2.1.03.08.0AScreening Decision: IncludedKeywords: Waste Package

Closure WeldsFabrication WeldsEarly FailureStress Corrosion CrackingEmplacement Error

FEP- Name: . MechN-.......: anica imact on wastre pckage >r .-................... -- ) -t-l8 iFEP Number: 2.1.03.07.OAScreening Decision: Excluded - Low ConsequenceKeywords: Waste Package

RockfallDrift CollapseSeismic Ground MotionVibrationDislodgmentDrip ShieldGas PressureCorrosion ProductsStress Corrosion Cracking

d~E Name: H .... ,,y drstatic resur onwaste p~ackaa-:.. --::. --i '<getji<4g

FEP Number: 2.1.07.04.OAScreening Decision: Excluded - Low ProbabilityKeywords: Waste Package

Hydrostatic Pressure

' Ne: . Creep of i etallic tcits1'ain 'th se tpacge .. <<I

FEP Number: 2.1.07.05.OAScreening Decision: Excluded - Low ConsequenceKeywords: Waste Package

Thermally-Induced CreepDeviatoric StressGas PressureInternal Void Space

i'FPtme Vneo .jme'i'eaeof rrosion products impacts waste packa'ge -;i '.5d52

FEP Number: 2.1.09.03.OBScreening Decision: Excluded - Low ConsequenceKeywords: Waste Package

Corrosion ProductsSwellingOxide Wedging

NOTE: Information is for illustration only, and is not an entry from the database

Figure 2. Example of a listing produced when the Waste Package - Mechanical cell is selected inFigure 1


The level of detail in the FEP list is a compromise between the number of FEPs in the list (forclarity as a list) and the depth of description for each FEP (for clarity of each item of the list).For any potential FEP, the discussion and description are subdivided repeatedly until the smallesttemporal or spatial scale is reached that is pertinent to barrier or total system performance.Simplifications to process models are developed with the scales of interest in mind. These typesof simplifications are discussed within the process AMRs themselves. Those AMRs also directlypoint to included FEPs at the level of detail of the FEP list. Each group of process AMRs feeds aFEP AMR, which repeats the inclusion arguments and adds arguments for excluded FEPs (inmany cases excluded FEPs are not associated with a specific process AMR).

Specific information to address NRC staffs additional information needs is provided in thefollowing sections.

2.1 ADDITIONAL INFORMATION NEEDS FOR TSPAI 2.05

The following provides the basis for addressing the nine AINs identified by the NRC for theTSPAI Agreement 2.05. Each item identified by the NRC staff includes a reference to the partof TSPAI Agreement 2.05 that is not addressed in sufficient detail, as appropriate(Schlueter 2002b). The response to each AIN follows the AIN text below.

AIN 1: "The schedule for making the significant decisions identified in the Enhanced FEP Plan;including those identified in Section 3.3 (e.g., configuration control, when AMR authors willhave the list of FEPs that they will need to address, FEP AMR updates, organization of the FEPmatrix)."

Response to AIN 1: The tasks listed in the Enhanced FEPs Plan, as modified by the generalchanges above, are the steps to develop the FEPs for TSPA-LA. The following tasks arecomplete at the time of this letter report:

* The process has been discussed with the AMR authors in a number of meetings.

* The database structure has been selected.

* The process and subsystem hierarchies are complete.

* The list of SR FEPs has been modified to produce a draft LA FEP list. Modificationsinclude splitting "broad FEPs" and mixed included/excluded FEPs into multiple FEPs,removing some "broad FEPs" that were completely addressed in multiple more specificFEPs, and identifying new candidate FEPs.

* A draft LA FEP list was distributed in January 2003 and has been updated twice sincethen.

* Software development of the database application is complete, and the software has beensubmitted for independent verification and validation.

* FEP AMR authors are aware of the screening process and documentation requirements.


The following tasks are ongoing:

* The FEP AMRs are being checked for concurrence with the Enhanced FEP Plan and theprocess changes identified herein, during the formal AMR review process.

* FEP configuration control includes reviews of Interface Exchange Documents (pertainingto the interface between the products of the repository design and performanceassessment organizations), with the reviews being used to identify needed changes to theFEP database and reconsideration of FEP screening arguments based on design changes.

* FEP configuration control includes use of the FEP database features to track changes tothe proposed FEPs and the associated screening arguments.

* Designers and AMR authors are being consulted on the need for additional candidateFEPs to be screened as the database is populated.

The following milestones are scheduled:

* The FEP database will be available in the Technical Management Database System, andthe supporting software will be available in the Software Configuration ManagementSystem in March 2004.

* The technical report documenting the FEP development process for TSPA-LA and thedatabase origins and contents will be available in the Controlled Document System inJune 2004.

AIN 2: "Information supporting the assertion that the approach of using keywords to describeFEP components will provide sufficient information on what has been considered or adescription of the approach that DOE will use to document what has been considered. Aspreviously discussed, a general example may help to illustrate the modified approach. [TSPAIAgreement 2.05 (1)]"

Response to AIN 2: Figure 2 herein provides an example of how keywords can describe and, insome cases, define the FEPs to be considered for screening. The keywords help to identifyspecific details of FEPs and facilitate navigation within the database. A FEP is defined by thecombination of the third-levels of the physical system and process hierarchies (i.e., a FEP matrixintersection) and the keywords; these are the basis for the FEP description in the AMRs and theFEP database. The FEP screening arguments will be documented at the level of detail necessaryto isolate the subprocesses or subsystems individually involved in the screening argument at thetemporal and spatial scales of interest for TSPA-LA. The keywords are the vehicle forsummarizing the level of detail at which a particular FEP is developed. FEP components will nolonger be used.

AIN 3: "Additional detail describing how DOE will apply its criteria on level of detail forredefining FEPs, so that it is clear how DOE will balance the competing goals of coarseness andspecificity when defining FEPs. As previously discussed, a general example may help toillustrate the proposed approach. [TSPAI Agreement 2.05 (2)]"


Response to AIN 3: The three-level subsystem and process hierarchies provide a description ofthe system and its performance that can be comprehended in a single view. Each subsystem-process matrix intersection defines the upper limit of coarseness for a FEP. The FEP screeningarguments will be documented in the FEP AMRs at the level of detail necessary to isolate thesubprocesses or subsystems individually involved in the screening argument at the temporal andspatial scales of interest for TSPA-LA. This will result in multiple FEPs for some matrix cells,corresponding to those technical areas with complex processes that need more detailedscreening. Inspection of the variations in the level of detail will be facilitated by the navigationfeatures of the database that will allow moving between the single high-level matrix view andviews of the individual FEPs and screening arguments within a single matrix cell. Figures 1 and2 herein illustrate the level of detail and the balance of coarseness and specificity.

AIN 4: "Adequate Justification for DOE's approach to limit a priori the number of FEPs toseveral hundred. [TSPAI Agreement 2.05 (2)]"

Response to AIN 4: There is, no a priori limit on the number of FEPs. The 328 primary SRFEPs are the starting point, and that number will increase as some FEPs are split to eliminatebroad FEPs and eliminate combined included/excluded FEP situations.

AIN 5: "DOE should clarify whether their Enhanced FEP Process will, or will not, lead toinstances where FEPs are considered both included and excluded. DOE should clarify where itbelieves this may be appropriate, why it believes that this result is appropriate, and shouldprovide examples illustrating this. [TSPAI Agreement 2.05 (6)]"

Response to AIN 5: The Enhanced FEPs Process will not lead to instances of single FEPs thathave both included and excluded elements. FEPs will be re-organized and subdivided wherenecessary, so that each FEP has a single screening decision.

AIN 6: "Additional detail regarding the methods that DOE will use to evaluate their approachagainst the Yucca Mountain Review Plan criteria (as excerpted) and the principles that will beused to guide the subjective evaluation that DOE plans to conduct. For example, it is unclearwhether audits of the pre-screening list of FEPs will be conducted to support the 'subjective'decision. [TSPAI Agreement 2.05 (7)]"

Response to AIN 6: The YMRP acceptance criteria inform the DOE about the metrics that NRCreviewers will use to evaluate the License Application. These criteria will be considered as theFEP database and screening arguments are developed. The FEP database is the top level of apyramid that includes the set of FEP AMRs and the larger set of process level AMRs. All threelevels undergo formal checking and technical discipline review as part of the productdevelopment process including review against the YMRP acceptance criteria. This work,combined with the prior work to develop the SR product, documents the evolution of the FEP listfrom the generic international database to the list that will be part of the License Applicationdocumentation.

AIN 7: "Clarify how DOE will address the completeness of the 'FEP components' consideredin the screening of FEPs or the modeling of FEPs and clarify how FEP components will beaddressed in the screening arguments for their associated FEPs. [TSPAI Agreement 2.05 (8)]"


Response to AIN 7: FEP components will no longer be used. However, there will be improvedclarity of the FEP database provided through the FEP-matrix-based organizational structure andthe capability to view it at a high enough level to comprehend its entirety. This will facilitate theFEP organization's evaluation of completeness and the subject matter experts' identification ofsubprocesses or subsystems not included in their modeling and screening arguments. Similarly,the clarity of the database will assist oversight bodies in developing independent assessments ofcompleteness. The mapping of the NEA classification list to the LA FEPs and the cross-referencing-of the SR FEP list to the LA FEPs will also facilitate evaluation of completeness.

AIN 8: "Clarify how the approach outlined in the Enhanced FEP Plan will not result in FEPsbeing designated FEP components issues nor will it lead to sufficient ambiguity as to make theFEP list incapable of being audited. [TSPAI Agreement 2.05 (10)]"

Response to AIN 8: The software view of the subsystem-process hierarchy will facilitatedevelopment of a FEP database free of ambiguities and omissions. Elimination of secondaryFEPs, FEP components, and combined include/exclude FEPs will reduce ambiguities and resultin a database that is transparent.

AIN 9: "Additional information clarifying how the Enhanced FEP Process will addressquestions of auditability, such as: (1) mutual exclusivity of FEPs (e.g., overlapping of FEPs) and(2) how auditability will be preserved with the proposed approach (i.e., the varying level of detailin defining FEPs and use of Hierarchical Level 4). [TSPAI Agreement 2.05 (12)]"

Response to AIN 9: The separation of the subsystem axis from the process axis in thehierarchical views of the database will highlight the mutual exclusivity of most of the boxes in atwo-dimensional view of the database. For those subsystem-process combinations with someoverlap (e.g., a thermal process column could overlap with several other process columns), thetwo-dimensional database view will identify the set of FEPs (through highlighting and/or listingrelated FEPs) that support the overlapping columns for a given subsystem row. This will makeevaluation of potential overlap more straightforward. The balance of the high level view and theFEP screening at the appropriate level of detail for the individual situation, combined with theelimination of FEP components, will also improve clarity. The traceability features included inthe LA FEP database will be an independent crosscheck back to the SR FEP list and to the NEAclassification list.

2.2 ADDITIONAL INFORMATION NEEDS FOR TSPAI 2.06

The following provides the basis for addressing the five AINs for the TSPAI 2.06 agreement.Each item identified by the NRC staff also includes a reference to the part of TSPAI Agreement2.06 that is not addressed in sufficient detail, as appropriate (Schlueter 2002b). The response toeach AIN follows the AIN text below.

AIN 1: "A description of the approach used to determine the degree of aggregation used todefine those FEPs appearing within the initial list of FEPs should be provided. This descriptionshould include a discussion of the important decisions made during its implementation and itshould address instances where FEPs are not mutually exclusive, if they were to occur. Theinformation provided should be have [sic] sufficient detail so as to allow the NRC to evaluate


whether hypothesized FEPs were, or were not, included in the initial list of FEPs and to supportits conclusions. Justification for the level of detail used to define FEPs that reflects the FEPs thatcomprise the pre-screening list of FEPs, where the justification includes an appropriatediscussion of the mutual exclusivity or overlapping of FEPs. If the number of FEPs in thepre-screening list of FEPs is limited because of a criterion used by DOE, justification for the useof this criterion needs to be provided. Justification for considering FEPs as both included andexcluded needs to be provided, if this approach is used by DOE. [TSPAI Agreement 2.06 (1)3"

Response to AIN 1: There is no limit on FEPs in the screening list (which is the sum of theincluded and excluded FEPs). The number of LA FEPs will be developed from the SR FEPs, thesplitting of some broad FEPs and mixed included/excluded FEPs (see AIN-4 for TSPAI-2.05),and from discussions with subject matter experts. The SR FEPs were developed iteratively usinginternational FEP databases, site-specific literature, and discussions and reviews within theproject. FEPs will only be aggregated if the screening argument applies across the range of theaggregation at the temporal and spatial scales of interest for TSPA-LA. The development of theLA FEPs will be documented in an AP-3.11 Q technical report. See the response to AIN-9 forTSPAI-2.05 for a discussion of exclusivity and overlap.

AIN 2: "Justification for the degree of consistency among FEPs reflecting the FEPs thatcomprise the pre-screening list of FEPs needs to be provided. The basis for why the FEPcomponents identified by the DOE should not be considered FEPs also needs to be provided.[TSPAI Agreement 2.06 (2)]"

Response to AIN 2: The FEPs components will be eliminated. The scope of each screeningargument will define the scope of the FEP it supports. See the response to AIN-3 for TSPAI-2.05 for a discussion of the balance between FEPs level of detail and the capability to view theFEP database globally.

AIN 3: "If DOE uses the criteria of multiple reviews by subject matter experts and externalreviewers as a basis for the completeness of the FEP list (pp. 37, 40), DOE should provide thedocumentation about the organization and nature of the reviews and how the review applies tothe list of FEPs initially considered (i.e., the pre-screening list of FEPs arising from theEnhanced FEP Process), describe the process used to conduct the review, and the results of eachreview. [TSPAI Agreement 2.06 (3)]"

Response to AIN 3: Pages 37 and 40 of the Enhanced FEPs Plan referred to the reviewsconducted in support of the SR, which are applicable to the LA FEP effort as well. In addition,the development of the LA FEPs includes technical staff review of prior work. As the LA FEPdatabase is populated and the AMR screening arguments are confirmed or modified, thecompleteness will be evaluated based on the overall database and its predecessors, including theNEA database. The LA FEP database will facilitate a review of the NEA FEPs (and theirmapping to the LA FEPs) and the SR FEPs (and their cross-referencing to the LA FEPs) byproviding electronic access to and searching of the FEPs in a single location. The formal reviewof the FEP list will be the review of the FEP technical report, which is prepared in accordancewith AP-3.1 lQ and reviewed in accordance with AP-2.14Q. The organization and nature of thereview process is prescribed by AP-2.14Q.


AIN 4: "Also, DOE should provide a rationale for why reviews of different FEP lists wouldapply to the completeness of the actual list, because there may be changes in level of detail, etc.DOE should clarify how previous reviews of different FEP lists will support assertions that theFEP list arising from the Enhanced FEP Process is sufficiently complete. This should include adiscussion of the role of FEP components and how they pertain to completeness of DOE'sconsideration of features, events, and processes. [TSPAI Agreement 2.06 (3)]"

Response to AIN 4: As noted in the Enhanced FEP Plan (BSC 2002, Section 2.3.1), the NEAstates that, "comprehensiveness ... will have to be judged against a record of continuous andopen reviews ... ". The past reviews of FEP lists are part of this continuous review process andsupport the completeness of the LA FEP list. The FEP Team has the responsibility to evaluatethe populated LA FEP database and to interact with subject matter experts, to ensure thecompleteness of the FEP list. The clarity features of the enhanced process are designed to enablethe completion of this task. As stated above, the simplifications described in this letter report,such as the elimination of FEP components, will support assessment of completeness. Inaddition, event trees and interface diagrams will be considered to support the demonstration ofcompleteness.

AIN 5: "If DOE uses the FEP matrix to support an assertion that its list of FEPs initiallyconsidered is complete, DOE needs to provide additional information that supports theappropriateness of the FEP matrix for this purpose. This additional information should describehow the organization and content of the, as described in Appendix A (A-l), FEP matrix, and itsuse, supports the assertion of completeness as an attribute of the pre-screening list of FEPs. IfHierarchical Level 4 is to be used to provide part of the technical basis for the completeness ofthe initial list of FEPs and it is not implemented uniformly, then additional information justifyingthe appropriateness of DOE's approach towards Hierarchical Level 4 should be provided.

Response to AIN 5: The responses to AIN-7 for TSPAI-2.05 and AIN-4 for TSPAI-2.06discuss the approach to evaluating completeness of the FEP list. FEP screening will be at thelevel of detail for which the screening logical argument is applicable, for each situation.

3. CONCLUSIONS

The Enhanced FEP Plan, the additional information in Section 2 of this letter report, and DOE'sproposal to meet periodically with NRC to provide progress assessments, collectively addressAgreement items TSPAI 2.05 and TSPAI 2.06 and the additional information needs for theseagreements.

4. REFERENCES

4.1 DOCUMENTS CITED

162463 Brocoum, S. 2002. "Transmittal of Report Addressing Key Technical Issues (KTI)."Letter from S. Brocoum (DOE/YMSCO) to J.R. Schlueter (NRC), April 5, 2002,0408022112, OL&RC:TCG-0844 [No Enclosures]. ACC: MOL.20020716.0095.


158966 BSC (Bechtel SAIC Company) 2002. The Enhanced Plan for Features, Events, andProcesses (FEPs) at Yucca Mountain. TDR-WIS-PA-000005 REV 00. Las Vegas,Nevada: Bechtel SAIC Company. ACC: MOL.20020417.0385.

159538 NRC (U.S. Nuclear Regulatory Commission) 2002. Integrated Issue ResolutionStatus Report. NUREG-1762. Washington, D.C.: U.S. Nuclear' RegulatoryCommission, Office of Nuclear Material Safety and Safeguards. TIC: 253064.

161434 Schlueter, J. 2002a. "U.S. Nuclear Regulatory Commission/U.S. Department ofEnergy Technical Exchange and Management Meeting on Key Technical IssueAgreements (April 15-16, 2002)." Letter from J. Schlueter (NRC) to S. Brocoum(DOE/YMSCO), April 15, 2002, 0506022546, with enclosure. ACC:MOL.20020724.0088.

161286 Schlueter, J. 2002b. "Total System Performance Assessment and IntegrationAgreement 2.05 and 2.06." Letter from J. Schlueter (NRC) to J.D. Ziegler(DOE/YMSCO), August 2, 2002, 0809023757, with enclosure. ACC:MOL.20021010.0014.

4.2 CODES, STANDARDS, REGULATIONS, AND PROCEDURES

162464 AP-2.14Q, Rev. 2, ICN 2. Review of Technical Products and Data. Las Vegas,Nevada: Bechtel SAIC Company. ACC: DOC.20030206.0001.

162500 AP-3.1 IQ, Rev. 3, ICN 4. Technical Reports. Washington, D.C.: U.S. Department ofEnergy, Office of Civilian Radioactive Waste Management. ACC:DOC.20030331.0002.
